A strong and shallow undersea earthquake shook western Indonesia on Monday, causing residents to panic, but there were no immediate reports of serious damage or casualties.

The quake caused panic in Siberut, a coastal town on Mentawai island, where people ran to higher ground, witnesses told The Associated Press. But no major damages were reported on Mentawai, the closest island to the epicenter.

The magnitude 6.4 earthquake posed no danger of triggering a tsunami, the Indonesian Meteorology, Climatology and Geophysics Agency said. Smaller earthquakes of 5.9 and 5.2 magnitude also shook the province earlier on Monday.

The U.S. Geological Survey measured the quake at magnitude 5.9 and said it was centered about 170 kilometers (105.6 miles) west-southwest of Pariaman, a coastal city in West Sumatra province at a depth of 18 kilometers (11 miles). Variations in early measurements are common.

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Indonesia is a seismically active archipelago of 270 million people that is frequently struck by earthquakes, volcanic eruptions and tsunamis.

In February, a magnitude 6.2 earthquake killed at least 25 people and injured more than 460 in West Sumatra province. In January 2021, a magnitude 6.2 earthquake killed more than 100 people and injured nearly 6,500 in West Sulawesi province.